When agricultural chemicals, such as fertilizers, herbicides, and pesticides are sprayed over an area, it is desirable to broadcast such chemicals over as large an area as possible during a single pass across a field. This minimizes the amount of time and energy expended and also minimizes the impact on the environment caused by the treading of the transportation equipment. The agricultural equipment most commonly used for spraying agricultural chemicals are booms. Most booms are attached to a tractor or placed in the rear of a pickup truck; some are even self-propelled. Because it is desirable to broadcast chemicals over as large an area as possible, boom lengths are generally relatively long, with most booms averaging between 60 and 90 feet in length. This long length poses many difficulties. First, the length of booms makes it difficult to move the boom from one location to another. Second, the length makes it difficult to maintain the necessary rigidity for proper spray patterns. Third, the length makes it difficult to design a boom that is able to avoid ground obstructions, with its spray nozzles and plumbing equipment. Thus, as booms travel over uneven and rough terrain, the boom is damaged from constant bouncing and jolting over ground obstructions. This bouncing and jolting often causes boom hinges and bearings to crack and structural members of the boom to bend.
A boom hinge is a specific boom design that uses a hinge device to connect the pieces comprising the boom, allowing only a limited angle of rotation between them. This angle of rotation allows the pieces of a boom hinge to fold, which in turn shortens the length of the boom hinge. Most boom hinge designs successfully carry out the function of folding; however there are a few problems with the prior art. In some boom designs, the actual folding introduces bending moments into the structures thereby requiring the structural members to be made with stronger and more costly materials. Other boom hinge designs lock the pieces that comprise the boom too tight, also causing the boom members to bend. Accordingly, there is a need in the art for an improved boom hinge design that carries out the folding and locking functions in a way that minimizes the bending of the structures. Such a design is beneficial because it will enable the boom to be made with lighter and less-costly materials.